A doctor started having an affair with his nurse. Shortly after this started, she announced that she had become pregnant. Not wanting his wife to find out, he gave her a large amount of money and asked her to go out of the country, to Germany, to wait out the pregnancy and have the baby over there.
"But, how will you know when our baby is born?" she asked.

"Well," he said, "after you’ve had the baby, just send me a postcard and write ’sauerkraut’ on the back."

Not knowing what else to do, she took the money and went off to Germany.

Six months went by and then one day the doctor’s wife called him at his office. "Dear, you received a very strange postcard in the mail today," she explained. "I don’t understand what it means!"

"Just wait until I get home and I’ll read it," he replied.

Later that evening, the doctor came home and read his postcard, which said: "Sauerkraut, Sauerkraut, Sauerkraut: Two with wieners, One without!"